[vorbis] Frequency response issues with native ogg vrs re-encoded ogg.

Gian-Carlo Pascutto gcp at sjeng.org
Mon Sep 10 05:08:17 PDT 2001

----- Original Message -----
From: <k_myers at irito.com>
To: <vorbis at xiph.org>
Sent: Monday, September 10, 2001 12:47 PM
Subject: [vorbis] Frequency response issues with native ogg vrs re-encoded

> I did the encoding
> to ogg with oggdrop (not exactly sure if that had the RC2 encoder in it).

I get 'Xiphophorus libVorbis I 20010813' tag when streaming it, so that
would indeed be RC2.

> When I stream mp3 I am using oddcast dsp
> beta 25 and of course that uses LAME with the settings using VBR "ABR"
> with no hi or low pass cut off.

Minor nitpick: ABR isn't a VBR mode but an enhanced CBR mode. LAME uses
a different (likely better) encoding setup when doing VBR compared to ABR.

> My problems seem to be the opposite of what people understand with mp3 vs
> Vorbis.

That's why it is so interesting :)

> (mastered with
> the effects) and encode to Vorbis 350kbps and MP3 (at 360kbps if I can get
> it that high.. not sure though as I am using Vegas 2.0 to do this)

I doubt it. The only way to get 360kbps MP3 would be a freeformat CBR
bitstream, which most tools can't handle.

Note that Vorbis 350kbps bitstreams are actually usually a fair bit lower
in actual bitrate.

> take the files back into wave format and put them through a set of
> analyzers running at the same time in sync and see what I get.

Using a frequency analyzer to judge perceptual codecs is tricky.

> Once I get a few tests completed, I will post the resulting files on my
> site or have them for DL somewhere.

Very well. Thanks!


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